Portable electronic devices (e.g., mobile phones, media players, smart watches, and the like) operate when there is charge stored in their batteries. Some portable electronic devices include a rechargeable battery that can be recharged by coupling the portable electronic device to a power source through a physical connection, such as through a charging cord. Using a charging cord to charge a battery in an electronic device, however, requires the portable electronic device to be physically tethered to a power outlet. Additionally, using a charging cord requires the portable electronic device to have a connector, typically a receptacle connector, configured to mate with a connector, typically a plug connector, of the charging cord. The receptacle connector typically includes a cavity in the portable electronic device that provides an avenue within which dust and moisture can intrude and damage the device. Furthermore, a user of the portable electronic device has to physically connect the charging cable to the receptacle connector in order to charge the battery.
To avoid such shortcomings, portable electronic devices have been configured with receiver coils that can receive power from a wireless charging device without the need for a charging cord. For example, some portable electronic devices can be recharged by merely resting the device on a charging surface of a wireless charging device. A transmitter coil disposed below the charging surface may produce a time-varying magnetic field that induces a current in a corresponding receiver coil in the portable electronic device. The induced current can be used by the portable electronic device to charge its internal battery.
Some existing portable electronic devices configured to receive wireless power have a number of disadvantages. For instance, some portable electronic devices require that it be placed in a very confined charging region on a charging surface of a wireless charging device in order to receive power. If the portable electronic device is placed outside of the charging region, the portable electronic device may not wirelessly charge or may charge inefficiently and waste power. Additionally, some portable electronic devices are configured to charge from only one type of wireless charging device. Thus, these portable electronic devices can only charge at one frequency and require the use of a specific type of wireless charging device. This limits the ease at which the portable electronic device can be wirelessly charged.
Furthermore, portable electronic devices, especially wearable portable electronic devices such as smart watches and the like, are designed to be compact so that they do not interfere with a user's mobility in his or her day-to-day activities. Having this compact design constrains the size limitations of internal components within the portable electronic device. As the functionality of the portable electronic devices increases, a larger number of electronic components will need to be housed within the portable electronic device, where some components will require larger amounts of space than other electronic components. Finding the right balance between size requirements of each internal component and its proper operation is difficult to achieve for such compact portable electronic devices.